MODELS FOR THE HOMOGENEOUS HYDRODESULFURIZATION OF BENZOTHIOPHENES - CARBON-SULFUR BOND-CLEAVAGE, HYDROGENOLYSIS, AND DESULFURIZATION REACTIONS MEDIATED BY COORDINATION OF THE CARBOCYCLIC RING TO MANGANESE ANDRUTHENIUM

Chemical reduction of a series of (eta(6)-benzothiophene)Mn(CO)(3)(+) complexes (10a-c) under CO affords neutral dimanganese metallathiacycl ic complexes (12a-c), which have a Mn(CO)(4) moiety inserted into the C(aryl)-S bond. Reduction of (eta(6)-benzothiophene)Ru(C6Me6)(2+) in t he presence of CO and (eta(6)-1-Me-naphthalene)Mn(CO)(3)(+) affords an analogous cationic bimetallic (15), which is converted to a neutral c yclohexadienyl complex (16) by hydride addition to the carbocyclic ben zothiophene ring. The sulfur atom in the metallathiacyclic ring in 12 and 16 is nucleophilic and reacts with electrophiles CF3SO3Me, HBF4, a nd W(CO)(5)(THF) to afford complexes such as 6, 14, and 17. Treatment of 12 with H-2 results in hydrogenolysis of the Mn-C sigma bond and fo rmation of the bimetallic Mn-2(CO)(8)(H)(SCH=CHPh) (8), which contains a Mn-Mn bond and bridging hydride and thiolate ligands. Reaction of 6 and 17 with H-2 results in desulfurization of the benzothiophene and formation of a mixture of Mn(CO)(5)SR and [Mn(CO)(4)SR](2) (R = H, Me) . Crystal structures are reported for 9 (R = Me), 12b, and 16.